Gas-shielded arc torch

ABSTRACT

A gas-shielded arc torch has a flexible shank between the head and the handle and is constructed to employ the inflowing gas to cool the electrode and head, thus maintaining high capacity in the torch, while permitting its production in reduced scale.

United States Patent Kleppen, Jr.

1451 Nov. 21, 1972 [72] lnventor:

[ GAS-SHIELDED ARC TORCH Arthur L. Kleppen, Jr., Kent, Wash.

[73] Assigneez Conley and Kleppen Enterprises,

Inc., Kent, Wash.

22 Filed: 0 6. 1,1971

21 Appl.No.:203 ,776

s2 u.s.c1...' ..219/7s,219/120,219/130 51 Int. Cl. ..B23k 9/16 [58]Field of Search .2l9/75, 74,130,121 P, 121, 219/138,70,120

[56] References Cited UNITED STATES PATENTS 3,238,350 3/1966 Klasson etal. ..2l 9/75 1/1958 Upton .......2l9/l20 X 2,820,075 2,943,183 6/1960Simms et al ..219/7s x 3,056,018 9/1962 Peterson ..219/75 x PrimaryExaminer-J. V. Truhe Assistant Examiner-B. A. Reynolds Attorney-Ford E.Smith [57 ABSTRACT A gas-shielded arc torch has a flexible shank betweenthe head and the handle and is constructed to employ the inflowing gasto cool the electrode and head, thus maintaining high capacity in thetorch, while permitting its production in reduced scale,

4 Claims, 3 Drawing Figures GAS-SHIELDED Anc TORCH BACKGROUND OF THEINVENTION It has been a continuing desire in the manufacture of arctorches (a) to reduce the dimensions of the torch to a minimum to permitworking in restricted areas; (b) to include flexibility between thehandle and the torch head to permit directing the electrode athard-to-reach locations; and (c) to maintain high capacity of the torchby providingv cooling functions. The customary practice as to torchcooling has been to provide coolant passages in the shank and headwhereby inflowing and reverse flowing coolant, such as water absorbs andcarries away heat. When the passages are small and restricted as when ahead is made very small the cooling efficiency is generally very low.Also, since the conduit means forming the coolant passages and gasconduit must be included in the handle and shank supporting the head, ithas been practically impossible to provide a flexible yet small andcompact arc torch and one easily manipulated.

Theprimary object of this invention is to reduce the size of the torchhead to provide a flexible shank while providing cooling efficiency andconsequent highcurrent-carrying capacity of gas-shielded arc torches.

SUMMARY OF THE INVENTION A metal torch head supports an electrode and agasdirecting nozzle and has a transversely disposed neck at one side bywhich gas is conducted into the head andelectrical current to theelectrode. The torch head is devoid of coolant passages and therefore,by comparison with prior constructions, may be very small and compact. Ahelical gas conduit of cylindriform is secured to the neck of the headand functions in part as a current conductor as well as a heat transfermember. Within the helical gas conductor, which is flexible, is anuninsulated multi-stranded main current conductor secured at its end bysolder techniques at remote parts of the gas-conducting helix providinga shortened electrical path without materially affecting flexibility.This current conductor is swelled during manufacture within .the coilsof the helix establishing intimate conmet with thelinner surfaces ofsuch coils for enhanced heat transfer functions. A molded elastomericinsulative body covers the head and said gas and current conductingassembly, thus providing a shank-covering that does not materiallyimpede flexibility of the helical element. A hollow non-conductivehandle is attached to the flexible shank. Gas and current supply conduitmeans are introduced into the rear end of the hollow handle and couplingwith the outer end of said flexible helical element takes place thereinand is shielded.

In the drawings:

FIG. 1 is an enlarged side elevation, primarily in axial section, of anarc touch according to this invention;

FIG. 2 is a cross-section on line 2-2 of FIG. 1; and

FIG. 3 shows in elevation the method of manufacture of the helical gasand current conductor element.

DESCRIPTION OF THE INVENTION Referring to FIG. 1, the arc torchcomprises the head supporting the electrode 12 which is surrounded bythe nozzle 14. At one side, head 10 has a neck 16 extending transverselyoutward, preferably inclined or head 10 the assembly is first packedabout with angled rearward with respect to the axis of head 10 and theelectrode.

Tubular handle 18, formed of insulative, non-conductiveplastic material,receives the end of gas conduit 20 which encloses conductor 21. Couplermembers 22, 24 are encased by handle 18.

Between coupler 24 and neck 16 is disposed the helical gas and currentconductive element or assembly 30, so designated as a whole. Element 30is in the form of a flexible cylindrical helix having an axial passagetherethrough;

Preferably element 30 is formed of copper tubing for rapid heat transferand high electrical conductivity. At its rear end element 30 has a shank32 engaged by coupler 24 and, at its other end, shank 34 is secured inneck 16. The length of element 30 may vary and, thus, may include moreor fewer coils than shown in FIG. 1 where, desirably, there are fivesuch coils.

Element 30 is produced by coiling tubing about a mandrel with a fairlylong lead as shown in FIG. 3. While in that extended condition anuninsulated multistranded electrical main conductor 36 is introducedinto the axial passage and, at its ends, soldered at 38 firmly toelement 30 near the end shanks 32/34. At this stage conductor 36 doesnot fill the axial passage. The spaces between coils of element 30 whennewly formed will be substantially greater than in the finishedassembly. Pressure,.as indicated by arrows in FIG. 3, is appliedoppositely to the ends 32/34 of element 30 which is compressedintermediately into a tighter helix. Such pressure causes the ends ofconductor 36 to close toward each other. The stranded conductor 36unlays itself and swells in the axial passage. This establishes contactwith a large portion of the interior surfaces of the helical coils asshown in FIGS. 1 and 2.

The mandrel-coiling of the tubing in forming element 30 tends to flattenor make oval the otherwise circular cross-section of the tubing. As aresult, when the multistranded conductor 36 is expanded or swelled asthe helix length is reduced very intimate contact of the conductor 36 onthe interior helix surfaces is established.

Whenshank 34 is seated and securedin neck 16 of elastomeric material 40,and then placed ina mold to shape and cure the elastomer and thuscomplete the main part of the torch. The head 10 is imbedded in thenon-conductive sheath 42 and the helical element 30 is imbedded in necksheath 44 which terminate with handle boss 46 to which is fitted thetubular handle 48.

It will be seen that that portion of the assembly between head 10 andhandle 48 may be flexed (as indicated by dotted lines in FIG. 1) tonumerous curvatures. Thereby the directional relation of the electrode12 to the manually manipulated handle 48 may be varied so that thewelder may conveniently direct the electrode at hard-to-reach positions.Flexing of the neck sheath portion 44 of the torch is accommodated bothby the constructional features of the helical element 30 and theelastomeric nature of sheath 44.

The preferred elastomeric material to form sheaths 42, 44 is a siliconerubber compound which is readily available, easy to mold, and one thatcures quickly.

In operation the coils of element 30 and the gas flowing therein do notappear to absorb heat from conductor 36', nor does element 30 heat up aswould be the case if the current flow were restricted to element 30.Conductor 36 provides a short path for the current flowing to theelectrode. It is observed that this avoids heating of element 30 andavoids heating of the gas which would otherwise occur if element 30served as the main electrical conductor.

Tests have shown that when helical element 30 is operated as the soleconductor of both gas and current the temperature of element 30 rises toa high level. lnevitably the temperature of the gas flowing to head 10can be such that little or no cooling is possible after an undesirablyshort time. In the same testing it was found that the addition of theconductor 36 as described appreciably reduced the rate of temperaturerise in element 30 and, hence, in the inflowing gas. This materiallydeferred the occurrence of undesirable temperature conditions at head10.

More specifically, tests were conducted with several torches inaccordance with MilSpec W-80l05A (26 Feb. 71). The torches werecontinuously operated for one hour each at 150 Amp. (DCSP). Atemperature measuring device was employed to read temperatures insidethe head of each torch.

With a torch having a straight and inflexible 3/16 inch brass tube inthe place of helix 30 after 1 hour a temperature of 5 25F. prevailed.

In a helical shank torch as disclosed herein, however not includingflexible conductor 36 within a 3/16 inch copper coil, the temperaturerose to 635F.

By comparison a torch as disclosed herein with a flexible helix 30 beingformed of 3/ 16 inch copper tubing and including a conductor 30 theattained temperature was 550F. after 1 hours continuous operation.

What is claimed is: 1. A gas-cooled, gas-shielded arc torch, comprising:an insulated torch head for supporting an electrode and a gas-directingnozzle surrounding said electrode, said head being devoid ofsupplemental coolant means;

a neck extending transversely from said head at one side for supplyingcurrent to said electrode and gas to said nozzle,

a gas and current conductive tubular metallic element in the form of acylindrical single helix having an axial passage therethrough;

a main current conductor in said axial passage secured conductively atits ends to portions of said element separated by several coils;

flexible insulative means covering said element;

gas and current supply means coupled to said element opposite said torchhead; and

handle means associated with said flexible insulative means tofacilitate manipulation of said torch.

2. The structure of claim 1 in which said main current conductor ismulti-stranded.

3. The structure of claim 2 in which said multistranded main currentconductor swells to substantially fill said axial passage.

4. The structure of claim 1 in which the flexible insulative means is acured elastomeric material.

1. A gas-cooled, gas-shielded arc torch, comprising: an insulated torchhead for supporting an electrode and a gasdirecting nozzle surroundingsaid electrode, said head being devoid of supplemental coolant means; aneck extending transversely from said head at one side for supplyingcurrent to said electrode and gas to said nozzle; a gas and currentconductive tubular metallic element in the form of a cylindrical singlehelix having an axial passage therethrough; a main current conductor insaid axial passage secured conductively at its ends to portions of saidelement separated by several coils; flexible insulative means coveringsaid element; gas and current supply means coupled to said elementopposite said torch head; and handle means associated with said flexibleinsulative means to facilitate manipulation of said torch.
 1. Agas-cooled, gas-shielded arc torch, comprising: an insulated torch headfor supporting an electrode and a gas-directing nozzle surrounding saidelectrode, said head being devoid of supplemental coolant means; a neckextending transversely from said head at one side for supplying currentto said electrode and gas to said nozzle; a gas and current conductivetubular metallic element in the form of a cylindrical single helixhaving an axial passage therethrough; a main current conductor in saidaxial passage secured conductively at its ends to portions of saidelement separated by several coils; flexible insulative means coveringsaid element; gas and current supply means coupled to said elementopposite said torch head; and handle means associated with said flexibleinsulative means to facilitate manipulation of said torch.
 2. Thestructure of claim 1 in which said main current conductor ismulti-stranded.
 3. The structure of claim 2 in which said multi-strandedmain current conductor swells to substantially fill said axial passage.